The present invention relates to a device for stirring molten metal in a continuous casting installation during the cooling of the cast product, and more particularly to the casting of wide, flat products, generally designated as slabs.
Devices for stirring liquid metal by means of linearly translating or rotating magnetic fields are known. These fields are produced by inductors located in the guide and support rollers for the continuously cast product. Such devices are described, for example, in French Patent Application No. 72/20,546, published under Patent No. 2,187,467 and in its first and second addition certificates Nos. 73/19,399 and 73/19,400, published respectively under Patent Nos. 2,231,454 and 2,231,455. French Pat. No. 2,187,467, without entering into the details of the construction of the inductor itself, teaches that an inductor may either be made integral with the roller and rotate with it, or may be supported fixedly inside the rotating roller. The first addition certificate No. 2,231,454 describes an embodiment of an inductor with a translating field which is integral in rotation with the hollow body of revolution wherein it is located. The inductor comprises a magnetic core in the form of an arbor of magnetic stainless steel, having a plurality of deep longitudinal grooves extending over the entire length of the arbor and spaced uniformly in the circumferential direction. A plurality of packets of flat magnetic sheets, disposed parallel to the axis of the arbor, are fitted into the grooves. The arbor and the sheets are notched by a series of annular slots that are spaced over the length of the arbor and house circular inductive coils.
The disadvantage of the devices described in the abovecited publications is the lack of power associated with them. It is conceivable that this lack of power is the result of the fact that the magnetic field produced by the inductor is distributed in azimuth in all directions around the axis of the roller. Consequently, the density of the magnetic flux emanating in the useful direction, i.e. toward the zone of contact between the roller and the slab, is weak because the magnetic flux is uselessly dispersed in the other directions, in particular in the direction opposite to the slab and in the direction of the adjacent rollers located upstream and downstream from the roller under consideration, with respect to the direction of movement of the casting.